Spontaneous scalarization: asymmetron as dark matter

TL;DR

This paper introduces a scalar-tensor model with a massive scalar field called asymmetron that causes spontaneous scalarization in dense objects, potentially explaining dark matter while remaining consistent with solar system tests.

Contribution

It extends previous models by incorporating a massive scalar field that accounts for dark matter and induces observable effects in dense astrophysical objects.

Findings

Asymmetron causes a significant reduction in gravitational constant inside neutron stars.

The model is consistent with solar-system and terrestrial gravity tests.

Spontaneous scalarization offers a new way to probe dark matter and gravity modifications.

Abstract

We propose a new scalar-tensor model which induces significant deviation from general relativity inside dense objects like neutron stars, while passing solar-system and terrestrial experiments, extending a model proposed by Damour and Esposito-Farese. Unlike their model, we employ a massive scalar field dubbed asymmetron so that it not only realizes proper cosmic evolution but also can account for the cold dark matter. In our model, asymmetron undergoes spontaneous scalarization inside dense objects, which results in reduction of the gravitational constant by a factor of order unity. This suggests that observational tests of constancy of the gravitational constant in high density phase are the effective ways to look into the asymmetron model.